1. Field of the Invention
The present invention relates to the preparation of a titanium on silica catalyst and to the use of the catalyst for the epoxidation of olefins to produce products such as propylene oxide.
2. Description of the Prior Art
A process for the epoxidation for olefins such as propylene to produce the oxirane product such as propylene oxide involves the reaction of the olefin with an organic hydroperoxide in the presence of various catalyst materials. The basic patent which describes this process is U.S. Pat. No. 3,351,635.
A particular embodiment of this technology which has been commercially practiced involves the use of a solid epoxidation catalyst comprised of titanium on silica. There are a number of patents which describe this embodiment of the technology including U.S. Pat. Nos. 3,829,392, 3,923,843, 4,021,454, 4,367,342, and British Patent 1,249,079.
Although good results have been achieved with the titanium on silica catalyzed epoxidation of olefins, there remains room for further improvement. It is an objective of the present invention to provide an improved epoxidation catalyst of the titania on silica type and to provide a process for the epoxidation of olefins using this catalyst.
In the technology associated with catalytic reduction of nitric oxide with ammonia the preparation of titania on silica catalysts has been described where the silica has been pretreated by refluxing in hydrochloric acid. See Applied Catalysis 69, p. 149-167 (1991), "Influence of the preparation method on the V.sub.2 O.sub.5 /TiO.sub.2 /SiO.sub.2 catalysts in selective reduction of nitric oxide with ammonia", Wauthog et al.